Propeller drive for oppositely rotating coaxial propellers



E. A. RYDER 2,154,532

PROPELLER DRIVE FOR OPPOSITELY ROTATING COAXIAL PROPELLERS pril 18,1939.

Filed y 14. 1936 L INVENTOR.

9- M ATTORNEY Patented Apr. 18, 1939 PROPELLER D RIVE ROTATING COAXIEarle A. Ryder, West FOR OPPOSI'I'ELY AL PROPELLERS Hartford. Conn,assignor to United Aircraft Corporation, East Hartford,

Conn.,

a corporation of Delaware Application May 14, 1936, Serial No. 79,644

Claims.

sistent with the size of the gear unit and the power to be transmitted.

Other objects and advantages will be more particularly pointed outhereinafter or will become apparent as the description proceeds.

rotating coaxial propellers from any suitable power plant. The numerall2 indicates a detach able nose section forming a as indicated at 32.

e inner propeller shaft 26 which carries the propeller 22 extends intothe hollow forward end of the drive shaft l4 and is there provided witha suitable spigot bearing 34.

propeller shafts against axial movement with respect to the engine. Theinner shaft 26 is restrained against axial the outer shaft 28 under theinfluence of propeller thrust by a suitable axial thrust bearing 40.

The drive shaft I4 is provided adjacent its fordrive gear 48 is securedto the bellhousing flange 44 by suitable means such as the annularflanges and bolts indicated at 50. The splines 42, bellhousing flange44, and annular gear 48 comprise the primary driving element of theimproved gear arrangement.

The outer propeller shaft or driven shaft 28 is provided adjacent itsrear end with a series of longitudinal splines 52 and upon these splinesthere is mounted a cage member generally indicated at 54. The cagemember 54 is made up of three separate parts, 58, 58, and 80, rigidlysecured together by means such as the through bolts 82. The intermediateportion 58 is provided with a cylindrical skirt portion 84 provided withinternal splines which engage with the splines 52 on the driven shaft toprovide a driving connection between the cage 54 and the driven shaft28.

This intermediate portion is also provided with a plurality of spacedbearings, one of which is indicated at 88.

Each of the planetary gears 88 is a compound gear having a reverse drivegear I integrally formed upon an elongated tubular shaft I2 providedwith three spaced apart annular bearing surfaces 14, I8, and I8, thereverse driving gear ll being formed between the intermediate bearingsurface I8 and one end bearing surface I4 and the portion of the shaftbetween the intermediate bearing surface 18, and the other end bearingsurface 18 being provided with external tends over the reverselongitudinal splines 88. Upon the splined portion 88 of each shaft,there is mounted a planetary gear element 82 provided with internalsplines which engage with the splines 80 to provide a driving connectionbetween the gear element and the axle upon which it is mounted, and withexternal gear teeth 84 which mesh with internal gear teeth 88 providedin the annular drive gear 48. The reverse drive gears 10 have a diametergreater than the diameter of the planetary gear elements 82 and aredisposed between these planetary gear elements and the bellhousingflange 44 so that the annular gear 48 is provided with an enlargedannular portion 88 which exdrive gears to the portion of the annulardrive gear 48provided with gear teeth meshing with the gear teeth of theplanetary gear elements 82. An inner center gear or sun gear, generallyindicated at 88, is fixed within the nose section I2 by suitable meanssuch as the bolts 82 which extend through the forward portion of thenose. section and engage in an annular flange 94 provided in the centergear. This center gear, is also provided with a cylindrical skirtportion 88 connected to the annular flange portion by a table filletportion 98 and provided with external gear teeth I88 which mesh with theteeth 84 of the planetary gear elements 82. The cylindrical portion 84of the intermediate part of the cage member 88 extends through thecylindrical portion 88 of the fixed center gear 88 and has a bearingtherein so that the cage is centered with respect to the engine by meansof the fixed center gear. I

A portion of the cage within the center gear is provided with suitableoil seal rings I02 and an oil passage I04 leads through the center gearfrom a control element such as the governor I88 to the space betweenthese oil seal rings from where an oil'passage I88 conducts the oil tothe interior of the outer shaft 28. The oil may then flow through thespace between the shafts 28 and 28 to the propeller pitch controllingmechanism 30, or if controllable pitch propellers are not used, the oilmay be used to lubricate the bearings 38 between. the two shafts.

The sun gear being fixed and meshing with the gear elements 82, willcause these elements to rotate upon rotation of the annular drive gear48 and to revolve about the center gear, thus when the drive shaft I4drives the annular drive gear 48, the cage 54 will rotate at a reducedspeed with respect to the speed of the drive shaft I4 and will carry'the outer driven shaft 28 with it, thus driving the propeller 24 in thesame direction as the direction of rotation of the drive shaft. At thesame time the rotation of the planetary gear elements 82 will cause thereverse drive gears III to rotate as they are being revolved about theaxis of the cage 54. The inner driven shaft 28 which carries thepropeller 22 is provided with an external gear IIII drivingly connectedthereto by suitable means such as the co-operating splines H2 andprovided with gear teeth which mesh with the teeth of the reverse drivegears III. As the reverse drive gears I8 have a diameter greater thanthe diameter of the planetary gear elements 82, their peripheral speedwill be greater than the peripheral speed of the planetary gearelements, by such an amount that as they are rotated by the progress oftheplanetary gear elements about the fixed center gear, their effectwill be to drive the gear I I0 and with it the shaft 28 backwardly at aspeed equal to the speed of rotation of the cage 54. Thus upon rotationof the annular drive gear 48 by the drive shaft I4, the two propellercarrying driven shafts 28 and 28 will be rotated in opposite directionsat a speed different from the speed of rotation of the drive shaft.

The gear H0 is maintained in operative position upon the shaft 28 by asuitable thrust nut H4 and bears at its forward end against the axialthrust bearing 40, the race element II8 of which is screw threaded uponthe end of the outer driven shaft 28 and is provided with an abutmentII8 which bears against the rearward end of the intermediate-portion 58of the cage 54 and maintains this portion of the cage in operativeposition upon the splined portion of the outer driven shaft 28. Theabutment H8 is preferably of a resilient material to permit a limitedamount of free axial movement between the cage and the outer drivenshaft.

From the above description, it will be observed that all three of theshafts are operatively connected to their associated elements of thegear train by means of axially slidable splined connections, suchconnections being provided both to facilitate the assembly of the gearmechanism and also to relieve the mechanism from any strain which mightbe imposed upon it by load strains carried by the various shafts. As thegear connection between the fixed center gear and planetary gearelements is also slidable in an axial direction, the cage and thecompound planetary gears carried thereby constitute a unitary devicewhich is radially centered with re-. spect to the fixed front portion ofthe engine and drive and driven shafts so that the mesh of the variousgears can not change, but which has a limited freedom of movement as aunit in an axial direction so that it will be relieved of allloadstrains carried by the drive and driven shafts.

With this arrangement of the gear elements the primary driving gearwhich transmits the power from the engine to the gear unit is made largewith a large number of gear teeth and consequent low tooth load betweenthe annular drive gear and the small planetary gears. The load betweenthe planetary gears and the sun gear is only gears mesh shaft an twicethat between the annular drive gear and propeller shaft is the same asthe load between sociated ele the planetary gears and-the sun gear. Thusthe 2. In a p shaft 28 and into its operative position and segears andrespective re cured to the engine crankcase It! so that the grallyformed on the s and arrangement of parts may be resorted to as eht fromthe s come within the scope of the appended claims. means ng.

Having now described the invention so that 1113- a rotatable th othersskilled in the art may clearly understand mediate P dllvi the same. whatit is desired to secure by Letters driven shafts p Patent is as follows:

What is claimed is:

1. In a propeller drive for oppositely rotating the same axle Carriement of said gear ropeller drive to of one of said coa While there hasbeen illustrated and described 4. In a propelle or opposite] shaft. anda difl'erent from the speed of said drive shaft, said driven shaftsmesh!" means comprising, a planetary gear tram 7 ears.

y rotating aft, a pair other driven shaft, and an annular bearingbetween said flxed center gear and said cage, and an oil lead forlubricating or propeller operating fluid extending through said fixedcenter gear and said cage to the interior of one of said driven 5shafts.

EARLE A. RYDER.

